Method of manufacturing battery electrode substrate and battery electrode substrate

ABSTRACT

Concave portions and convex portions are formed on a peripheral surface of a thin metal sheet by applying a pressing force thereto while the metal sheet is being embossed; pores are each formed on an apex of each of the concave portions and convex portions and burrs each projecting outward from a peripheral edge of each of the pores are generated by the pressing force; the metal sheets having the concave portions and convex portions formed thereon are layered on each other; the burr at the apex of each convex portion of a lower-layer metal sheet is interlocked with the burr at the apex of each concave portion of an upper-layer metal sheet adjacent to the lower-layer metal sheet to integrate the metal sheets with each other; and an active substance is charged into spaces between the upper-layer metal sheet and the lower-layer metal sheet through an aperture at the apex of each of the concave portions and convex portions.

TECHNICAL FIELD

[0001] The present invention relates to a method of manufacturing aplate for a battery electrode and the plate for a battery electrodemanufactured by the method, and more particularly to the plate for anelectrode which is preferably used for a supply battery of an electriccar because of a great thickness thereof to increase the amount of anactive substance to be applied thereto and because of a preferablecontact thereof with the active substance applied thereto to prevent itfrom dropping therefrom.

BACKGROUND ART

[0002] Heretofore, generally, as the plate of an electrode for using apositive electrode and a negative electrode of a nickel/hydrogenbattery, a nickel/cadmium battery or the like, principally, apore-formed nickel-plated steel plate (hereinafter referred to aspunching metal) formed by plating an iron plate on which pores areformed by punching is used. An active substance is applied to thepunching metal to form the electrode. In the case of a cylindricalbattery, the electrode comprising belt-shaped positive and negativeelectrodes is spirally wound through a separator to accommodate themtherein. In the case of a rectangular or. square battery, positive andnegative electrodes are layered on each other through a separator toaccommodate them therein.

[0003] The punching metal is used as the plate for a battery electrodeby punching a flat cold-rolled steel plate having a thickness of 60m-100g m to form thereon circular pores, the diameter of which is 1.0mm-2.5 mm in a required pattern such that the open area percentagethereof is 40%-50% and then nickel-plating the steel plate to keep itresistant to corrosion.

[0004] As the plate of an electrode consisting of positive and negativeelectrodes of a lithium primary battery, mainly, a lath processed frommetal such as SUS and Ti is used. The lath is charged with an activesubstance to form the electrode. In a lithium secondary battery, theactive substance is applied in a required thickness to both surfaces ofa metal core material made of an aluminum foil to form a positiveelectrode, and the active substance is applied in a required thicknessto both surfaces of a metal core material made of a copper foil to forma negative electrode.

[0005] As the plate of an air electrode to be used as the positiveelectrode of an air zinc battery, mainly, a metal screen (nickel-platedSUS mesh) is used. As a zinc storage battery which attracts publicattention recently as a car battery, a cast lattice or an expandedlattice consisting of lead alloy (Pb/Sb alloy, Pb/Ca alloy, Pb/Ca/Snalloy or the like) is used. The active substance is applied to thescreen and the lattice to form the electrode.

[0006] Further, in recent years, as the plate of the electrode of thenickel/hydrogen battery, the nickel/cadmium battery, and the lithiumprimary battery, porous metal sheets formed by chemically platingresinous foamed materials, nonwoven cloths or mesh materials to makethem electrically conductive, and then electroplating them, and then,removing resinous materials and sintering them are also used.

[0007] Any of the above-described plates for a battery electrode areflat. An active substance is applied to both surfaces thereof to fill itinto pores formed thereon and coat both surfaces thereof with the activesubstance in a required thickness. Because the above-described punchingmetal, the lath, and the metal screen are not three-dimensional, theyare not in close contact with the active substance and thus have a lowactive substance-holding force. In particular, if they have large poresformed thereon, the active substance is likely to separate and droptherefrom during the manufacture and use of an electrode. In order tosolve the problem, a method of adding a large amount of binder to theactive substance to prevent it from separating and dropping from theplate is known. But when a large amount of binder is added to the activesubstance, the reactivity of the active substance deteriorates, and thusthe battery characteristic is inferior.

[0008] The active substance is filled into pores of the foamed porousmetal sheet having a three-dimensional structure. Thus, the porous metalmaterial has a higher active substance25 holding property than thepunching metal and the metal screen. But in the foamed porous metalmaterial, the skeleton thereof surrounding the pores is not thick. Thus,the foamed porous metal material has a low electricity-collectingperformance, thus being incapable of accomplishing a rapid electriccharge or discharge when a rapid electric charge or discharge isrequired.

[0009] Because any of the conventional plates for an electrode is thin,the active substance is thinly applied thereto in the thicknessdirection thereof. Therefore, the electrode has a low electricalconductivity in its thickness direction. Thus, it is difficult toimprove the characteristic of the battery.

[0010] In order to solve this problem, in Japanese Laid-Open PatentPublications Nos. 7-130370 and 7-335208, there are proposed electrodeshaving an apparent thickness twice as great as that of a metal plate ora metal foil, including the thickness of burrs each formed on theperiphery of each of pores formed on the metal plate or the metal foilby using upper and lower dies. However, when pores are formed by a pairof dies, the maximum open area percentage is about 50%. Further, it isdifficult to form many fine pores on the entire surface of the metalplate or the metal foil by reducing the diameter of each pore and thepitch between the pores. Therefore, even though the burr is formed onthe periphery of each pore, the burr has a low occupation percentage andan insufficient active substance-holding force. In addition, because thediameter of each pore is large, the active substance charged into thepores is likely to be dropped therefrom. Further, because the pitchbetween the pores is long, the area of the metal foil or the metal plateis great, which prevents movement of ions in the active substance. Thus,these electrodes cause batteries to have inferior performance. In orderto solve these problems, it is conceivable to reduce the diameter ofeach pore and the pitch between the pores. But it is technically verydifficult and very costly to form the pores by a pair of upper and lowerdies as described above. Furthermore, only one metal plate having burrsformed thereon does not allow the application amount of the activesubstance to be increased so much.

[0011] The present invention has been made in view of theabove-described problems. It is accordingly an object of the presentinvention to provide a method of manufacturing a plate for a batteryelectrode which holds an active substance thereon firmly and allows alarge amount of the active substance to be applied thereto in thethickness direction thereof and provide the plate for a batteryelectrode manufactured by the method.

DISCLOSURE OF THE INVENTION

[0012] In order to solve the above-described problem, firstly, there isprovided a method of manufacturing a plate for a battery electrodecomprising the steps of: passing a thin metal sheet between a pair ofembossing rotation rollers having concave portions and convex portionsformed on a peripheral surface thereof to form concave portions andconvex portions on an entire surface of the metal sheet, and form poreseach on an apex of each of the concave portions and convex portions andgenerate burrs each projecting outward from a peripheral edge of each ofthe pores by a pressing force during formation of the concave portionsand convex portions.

[0013] According to the above-described method, by merely passing themetal sheet between a pair of the embossing rotation rollers,comparatively fine concave portions and convex portions can be formed onthe entire surface thereof, and at the same time, pores are each formedon the apex of each concave portion and convex portion, and the burr canbe projected from the peripheral edge of each pore. Thus, according tothe method utilizing the embossing method, compared with theconventional method of forming pores by means of upper and lower dies,the diameter of each pore which is formed on the apex of each concaveportion and convex portion and the pitch between the concave portionsand that between the convex portions can be allowed to be smaller.Therefore, the pitch between the pores each formed at the apex of eachof the concave portions and convex portions can be reduced greatly andthe open area ratio, namely, the ratio of the area of the pore to thearea of the metal sheet can be allowed to be much larger than that ofthe metal sheet formed by the conventional method using the dies.Because the burr is generated at the apex of each of the concaveportions and convex portions formed densely on the entire surface of themetal sheet, the ratio of the area of the burr to the area of the metalsheet can be allowed to be much higher than that of the metal sheetformed by the conventional method.

[0014] As described above, fine concave portions and convex portions areformed on the entire surface of the metal sheet, the pores are eachformed on the apex of each concave portion and convex portion, and theburrs are each generated on the periphery of each of the pores. Thus, anactive substance which can be applied to the metal sheet can be chargedinto the concave portions and the convex portions and held by the burrseach generated on the periphery of the apex of each of the concaveportions and convex portions. Hence, the charge amount of the activesubstance can be allowed to be much greater than that of the activesubstance which is applied to the metal sheet by the conventionalmethod. Further, the active substance can be held by the concaveportions and the convex portions reliably because the portions are fineand also held reliably by the burrs because the burrs are presentdensely on the surface of the metal sheet. Thus, the force of holdingthe active substance can be allowed to be much greater than the force ofholding the active substance which is applied to big pores formed atlong pitches by the conventional die. In addition, because the open arearatio is high, ions of the active substance move actively, thusimproving the performance of a battery.

[0015] More specifically, by forming the concave portions and convexportions on the metal sheet itself, the apparent thickness of the metalsheet can be allowed to be a desired thickness 3 to 500 times as largeas that of the metal sheet. For example, when convex portions are formedupward and downward on the metal sheet having a thickness of 10 μm tomake the thickness thereof 4 mm, the apparent thickness thereof is 400times as large as the thickness thereof.

[0016] Further, secondly there is provided a method of manufacturing aplate for a battery electrode comprising the steps of: passing a thinmetal sheet between a pair of rotation rollers, one of which is anembossing roller having concave portions and convex portions formed on aperipheral surface thereof and a other of which is rubber roller havingsmooth outer surface, to form pores on the metal sheet and generateburrs each projecting toward one side from a peripheral edge of each ofthe pores by pressing the rubber rollers against the convex portions ofthe embossing roller.

[0017] According to the above-described second method, although clearconcave portions and convex portions are not formed on the metal sheetitself, a large number of pores are formed on the entire surface thereofand a burr projecting in one direction (toward rubber roller) from eachpore can be formed. Thus, when the burr is desired to be projected inonly one direction, the second method can be preferably used.

[0018] Further, thirdly there is provided a method of manufacturing aplate for a battery electrode comprising the steps of: passing a thinmetal sheet sequentially between first and second sets of rotationrollers each consisting of an embossing roller having concave portionsand convex portions formed on a peripheral surface thereof and rubberroller having smooth outer surface to form pores on the metal sheet andgenerate burrs each projecting toward one side from a peripheral edge ofeach of the pores by pressing the rubber roller against said convexportions of the embossing roller when the metal sheet is passing betweenthe embossing roller and the rubber roller of the first set; and passingthe metal sheet between the embossing roller and the rubber roller ofthe second set to form pores on the metal sheet at different positionsthereof and generate burrs each projecting toward the other side fromthe peripheral edge of each of the pores.

[0019] Further, fourthly, there is provided a method of manufacturing aplate for a battery electrode. In the fourth method, metal sheets of thesame kind or different kinds, according to the first, second, and thirdmethods, having the pores and the burrs each projecting from theperipheral edge of each of the pores are layered one upon another; andthe burrs of an upper layer metal sheet and the burrs of a lower layermetal sheet adjacent to the upper layer metal sheet are interlocked witheach other to integrate the upper layer metal sheet and the lower layermetal sheet with each other; and spaces between the upper layer metalsheet and the lower layer metal sheet are communicated with each otherthrough the pores.

[0020] That is, the above-described “same kind” includes the case inwhich the plates described in the first method are layered one uponanother or the plate described in the second method or the platedescribed in the third method are layered one upon another. Theabove-described “different kinds” include the case in which the platedescribed in the first method and the plate described in the secondmethod are layered one upon another or the plate described in the firstmethod and the plate described in the third method are layered one uponanother and the plate described in the second method is layered on thesurface at both sides thereof.

[0021] In a metal sheet on which burrs are each formed on the peripheraledge of each of the pores by the first method through the third method,a large number of pores is formed by the embossing roll. Thus, the burrseach projecting from the peripheral edge of each pore are present on thesubstantially entire surface of the metal sheet. When these metal sheetsare layered one upon another, the burrs are interlocked with each otherand thus the metal sheets can be integrated with one another. Further,the metal sheets layered one upon another through the interlocking ofthe burrs do not make close contacts, but spaces are generated betweenlayered metal sheets. The spaces communicate with one another throughthe pores. Thus, when an active substance is charged into the layeredmetal sheets, the active substance can be reliably charged between themetal sheets.

[0022] Further, the present invention provides a plate for a batteryelectrode manufactured by any one of the above-described methods.

[0023] Preferably, there is provided a plate for a battery electrodewhich is manufactured by the fourth method and comprises a metal sheet,according to the first method, having pores each formed on an apex ofeach of concave portions and convex portions and burrs each projectingoutward from a peripheral edge of each of the pores and metal sheets,according to the second method, having burrs projecting toward one side.The metal sheets according to second method are layered on a surface atboth sides of the metal sheet according to the first method andsandwiching the metal sheet according to the first method therebetween.The burrs are projected toward an inner surface side of the metal sheetsaccording to the second method.

[0024] Preferably, there is provided a plate for a battery electrodecomprises a metal sheet, according to the third method, having burrseach projecting toward both directions from a peripheral edge of each ofthe pores and metal sheets, according to the second method, having burrsprojecting toward one side. The metal sheets according to second methodare layered on a surface at both sides of the metal sheet according tothe third method and sandwiching the metal sheet according to the thirdmethod therebetween. The burrs are projected toward an inner surfaceside of the metal sheets according to the second method.

[0025] Two burr-projected metal sheets may be layered one on the otherto project the burrs outward from both sides thereof.

[0026] As the center plate sandwiched between the upper and lowerplates, it is possible to use the plate manufactured by the first methodsuch that it has a great thickness because of concave portions andconvex portions formed thereon or the plate manufactured by the thirdmethod such that it has a great thickness because of burrs projectedfrom both sides thereof so as to increase the charge amount of theactive substance.

[0027] As the upper and lower plates, it is possible to use the platemanufactured by the second method such that it has burrs projected inonly one direction so as to project the burrs inward not outward.

[0028] In particular, because the plate manufactured by the first methodhas fine concave portions and convex portions densely, the charge amountof the active substance can be increased and the activesubstance-holding force can be increased by filling it into the spacessurrounded with the concave portions and convex portions. Even one metalsheet has an increased application amount of the active substance. Thus,a plate consisting of a plurality of the metal sheets which are layeredone upon another can be charged with more active substance. Further, thethickness of the plate for a battery electrode can be easily adjusted bymerely adjusting the number of metal sheets which are layered one uponanother. Thus, it is possible to provide the plate for a batteryelectrode which can be charged with a necessary amount of the activesubstance.

[0029] It is preferable to use a metal foil or/and metal sheet which isformed by rolling metal powder into a sheet. That is, a nickel foil, acopper foil, and an aluminum foil can be preferably used as a metalfoil.

[0030] As the metal sheet which is formed by rolling the metal powderinto a sheet, the metal sheet, formed by rolling the metal powder by apattern roller, proposed by the present applicant and disclosed inLaid-Open Japanese Patent Publication No. 8-122534 can be preferablyused. The metal sheet is formed by supplying metal powder to theperipheral surface of one pattern roller of a pair of pressure rollers,and then rolling the metal powder on the peripheral surface of thepressure roller directly by the rotation of a pair of the pressurerollers.

[0031] A metal sheet consisting of Ni, Al, Cu, Fe, Ag, Zn, Sn, Pb, Sb,Ti, In, V, Cr, Co, C, Ca, Mo, Au, P, W, Rh, Mn, B, Si, Ge, Se, La, Ga,Ir or an alloy of these elements can be preferably used theabove-described metal sheet.

[0032] In the plate for a battery electrode manufactured by the firstmethod, it is preferable to set the pitch between the concave portionsand that between the convex portions to 0.5 mm 2.0 mm and the height ofthe concave portion and that of the convex portion to 0.1 mm-2 mm.

[0033] The present invention provides an electrode for a battery inwhich an active substance is charged into spaces in the plate for abattery electrode. In the electrode, because pores are each formed onthe apex of each of fine concave portions and convex portions denselyformed on the entire surface of the metal sheet, the pores are chargedwith the active substance and surrounded with the burrs each formed onthe peripheral edge of each of the pores. Thus, the active substancehardly drops from the plate.

[0034] The active substance may contain an electrically conductivematerial. That is, with the increase in the volume of the activesubstance-application space surrounded with the metal sheets layered oneupon another, the charge amount of the active substance increases.Normally, as the active substance does not contain an electricallyconductive material, the electrically conductivity is a problem. Thus,it is preferable that the active substance contains the electricallyconductive material when the volume of the active substance-applicationspace is great and the active substance has a low electricalconductivity. Further, the present invention provides a battery havingthe above-described electrode for a battery. Because the electrode isthick and can be charged with a large amount of the active substance, itcan be preferably used as the supply battery of an electric vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1 is a sectional view showing a plate for a battery electrodeaccording to a first embodiment of the present invention;

[0036]FIG. 2 shows a method of manufacturing each metal sheetconstituting the plate of the first embodiment:

[0037]FIG. 2A is a schematic entire view, and

[0038]FIG. 2B is a main part-enlarged view;

[0039] FIGS. 3 is a drawing for explaining the shape of concave portionsand convex portions which are formed on the metal sheet constituting theplate for a battery electrode of the first embodiment:

[0040]FIG. 3A is a perspective view, and

[0041]FIG. 3B is a plan view;

[0042]FIG. 4 is a sectional view showing a state in which the plate fora battery electrode of the first embodiment is charged with an activesubstance to form an electrode;

[0043]FIG. 5 is a sectional view showing a case in which the layer modeof metal sheets are varied from that of the first embodiment;

[0044]FIG. 6 is a view showing the process of manufacturing a metalpowder sheet;

[0045]FIG. 7 is a schematic view showing a manufacturing method of asecond embodiment;

[0046]FIG. 8 is a sectional view showing a plate manufactured in thesecond embodiment;

[0047]FIG. 9 is a sectional view showing a state in which the plates ofthe second embodiment are layered on each other;

[0048]FIG. 10 is a sectional view showing a modification of the secondembodiment;

[0049]FIG. 11 is a schematic view showing a manufacturing method of athird embodiment;

[0050]FIG. 12 is a sectional view showing a plate manufactured in thethird embodiment;

[0051]FIG. 13 is a sectional view showing a state in which the plates ofthe third embodiment are layered on each other;

[0052]FIGS. 14A, 14B, and 14C are sectional views each showing amodification of the layer mode; and

[0053]FIG. 15 is a view showing a modification of a metal sheet which isembossed.

BEST MODE FOR CARRYING OUT THE INVENTION

[0054] The embodiments of the present invention will be described belowwith reference to drawings.

[0055]FIGS. 1 through 5 show the first embodiment of the presentinvention. A plate (S) for a battery electrode of the first embodimentis constructed by layering a large number of metal sheets 1 each ofwhich consists of a nickel foil having a thickness 10 μm-100 μm (15 μmin this embodiment) and which has concave portions and convex portionsformed on its entire surface by embossing the sheet.

[0056] As shown in FIG. 2, the method of manufacturing each of theabove-described metal sheets 1 is carried out by passing a thin flatmetal sheet 1 between embossing rolls 20A and 20B and between theembossing roll 20B and an embossing roll 20C. In the above-describedembossing rolls 20A, 20B and 20C, pyramidal fine convex portions 21 aredensely formed on the entire outer surface thereof, and pyramidalconcave portions 22 are formed between the convex portions 21.Initially, when the metal sheet 1′ is passed between the embossing rolls20A and 20B rotating in directions opposite to each other, the convexportion 21 at the embossing roll 20B fits in the concave portion 22 atthe embossing roll 20A, with the metal sheet 1′ sandwiched between theembossing rolls 20A and 20B. As a result, a convex portion 2 projectingpyramidally and a concave portion 3 concaving pyramidally are formed onthe metal sheet 1′ at the portion thereof sandwiched between theembossing rolls 20A and 20B. Then, when the metal sheet 1′ is passedbetween the embossing rolls 20B and 20C, the concave portion and convexportion of the embossing roll 20B and those of the embossing roll 20C sofit in each other that a convex portion is formed on the position of theconvex portion 2 and that a concave portion is formed on the position ofthe concave portion 3. By forming the concave portions and the convexportions at two times, the metal sheet 1′ is formed into a metal sheet 1having the pyramidal convex portions 2 and the pyramidal concaveportions 3 formed clearly thereon, as shown in FIG. 3.

[0057] Further, when the metal sheet 1′ is passed between the embossingrolls 20A and 20B and between the embossing rolls 20B and 20C, apressing force is applied to apexes to form pores 2a and 3a. Due to theformation of the pores, burrs 8 are formed in the peripheral edge of thepores 2a and 3a, thus projecting outward from the peripheral edge of thepores 2a and 3a. Because the pressing force is applied to the sameposition at two times by the embossing rolls 20A and 20B and theembossing rolls 20B and 20C, the pore can be reliably formed at the apexof each concave portion and each convex portion to which the pressingforce is applied at the greatest degree, and the burr can be generatedfrom the peripheral edge of each pore. As described above, as shown inFIGS. 3A and 3B, the pyramidal upward convex portions 2 projected upwardand the pyramidal concave portions (downward convex portion) 3 projecteddownward are formed alternately with each other lengthwise andwidthwise. In FIG. 3B, the concave portions 3 are indicated with obliquelines. That is, the periphery of each convex portion 2 is surroundedwith the concave portions 3, and each concave portion 3 is surroundedwith the convex portions 2 such that the convex portions 2 and theconcave portions 3 are continuous with each other to form the metalsheet 1 of only the concave portions 3 and the convex portions 2.

[0058] Further, in the embossing shown in FIG. 2, the apex of each ofthe convex portions 2 and that of each of the concave portions 3 arebroken to form the pore 2a on the apex of each of the convex portions 2and the pore 3a on that of each of the concave portions 3, and the burr8 spreads outward from the peripheral edge of each of the pores 2a and3a.

[0059] That is, it is possible by one processing to form the concaveportions and the convex portions, the pores each at the apex of each ofthe concave portions and the convex portions, and the burrs 8 eachextending outward from the peripheral edge of each pore.

[0060] In the first embodiment, the pitch between the convex portions 2(and pitch between concave portions 3) is 0.7 mm, the height of eachconvex portion 2 and the depth of each concave portion 3 are also 0.7mm, and the entire thickness of the metal sheet 1 obtained by theaddition of the convex portion 2 and the concave portion 3 is 1.4 mm.

[0061] When the metal sheets 1 are layered vertically one upon another,as shown in FIG. 1, the burrs 8 are interlocked with 25 each othervertically. The burrs 8 are fused into each other (welded to each other)and fixed to each other securely to integrate with each other the metalsheets 1 layered vertically one upon another. In particular, the convexportions 2 and the concave portions 3 are formed at a pitch of 0.7 mm,respectively; the pitch is very short; and the height of the convexportion 2 and the depth of the concave portion 3 are also as small as0.7 mm. Thus, in the state in which the metal sheets 1 are layeredvertically one upon another, the convex portions and the concaveportions are hardly coincident with each other, respectively. Further,because the burrs 8 are each projected from the apex of each of theconcave portions and convex portions, the metal sheets 1 are layeredvertically one upon another not in close contact, but in the state asshown in FIG. 1, with a large number of spaces 4 formed.

[0062] In the plate (S) for a battery electrode of the first embodimentconsisting of the metal sheets 1 layered one upon another, there areformed the spaces 4 whose periphery is a surrounded with the pyramidalconvex portions 2 and concave portions 3 of each metal sheet 1 and whoseupper and lower open surfaces are surrounded with the metal sheets 1positioned adjacently to each other; and the spaces 4 communicate withone another through the pore 2a at the apex of the convex portion 2 andthe pore 3a at the apex of the concave portion 3. In this manner, it ispossible to form the thick plate (S) for a battery electrode havingtherein a large number of large-volume spaces 4 surrounded with wallsconsisting of the metal sheets 1.

[0063] When an active substance 5 is charged into the plate (S) for abattery electrode having the above-described construction, the activesubstance 5 can be smoothly charged into the spaces 4 formed by layeringmetal sheets 1 one upon another through the pores 2a and 3a, because thepore 2a is formed at the apex of each convex portion 2 and the pore 3ais formed at the apex of each concave portion 3. That is, a plate for abattery electrode having the construction shown in FIG. 4 can be formed.

[0064] As described above, the layer mode of the metal sheets 1 is notlimited to that shown in FIG. 1. Even in the state as shown in FIG. 5 inwhich the convex portion 2 of the upper-layer metal sheet 1 ispositioned on the convex portion 2 of the lower-layer metal sheet 1, theburr 8 formed at the peripheral edge of the pore 2a positioned at theupper end of the convex portion 2 of the lower-layer metal sheet 1 isinterlocked with the burr 8 formed in the peripheral edge of the pore 3apositioned at the lower end of the concave portion 3, of the upper-layermetal sheet 1, adjacent to the convex portion 2. By fuzing the burrs 8into each other or welding to each other, it is possible to integratewith one another the metal sheets 1 which are layered one upon anothervertically.

[0065] Even not in the mode of layering the upper and lower metal sheetsshown in FIG. 1 and FIG. 5, i.e., even though the convex portion 2 andthe concave portion 3 are spaced at a half pitch, the upper and lowerlayers can be integrated with each other by interlocking the burr 8projecting from the peripheral edge of the apex of the concave portionwith the burr 8 projecting from the peripheral edge of the apex of theconvex portion.

[0066] Although the nickel foil is used in the first embodiment, it isalso preferable to use a non-porous metal sheet formed of metal powder,by using a pressure roller. The method of manufacturing a metal sheetfrom the metal powder is carried out by using a pair of flat pressurerollers 11 and 12, as shown in FIG. 6.

[0067] That is, above the roller 11, a sieve 13 having a mesh portion13a formed on the bottom surface thereof is vibrated in a right-to-leftdirection by a vibrating device 14 supporting the sieve 13 to spreadmetal powder (P) over the upper surface of the roller 11. To supply thesieve 13 with the metal powder (P), a predetermined amount of the metalpowder (P) is supplied from a material hopper 15 to a feeder 16. As themetal powder (P), nickel powder in the shape of spike and havingdiameters 2-7 μm is used. The spread metal powder (P) accumulates to apredetermined thickness on the peripheral surface 11b of the roller 11to form thereon a layer having a predetermined thickness. When a pair ofthe rollers 11 rotate in contact with the flat roller 12 in this state,at the portion of contact between the roller 11 and the roller 12, themetal powder (P) on the peripheral surface 11b of the roller 11 iscompressed by the flat roller 12 at a load of 15 tons and rolled as athin compressed metal sheet 1′.

[0068] The metal sheet 1′ rolled by the pressure rollers is continuouslyfed to a sintering oven 25 in which it is sintered by heating it in anonoxidizing atmosphere at 750° C. for about 15 minutes. Thereafter, themetal sheet 1′ is passed between pressure rollers 26 and 27 eachconsisting of a flat roller heated to 300° C.-400° C. to roll it againby applying a load of five tons thereto while the metal sheet 1 is beingheated. Then, the metal sheet 11 is continuously fed into a sinteringoven 28 to sinter it in a nonoxidizing atmosphere at 1,150° C. for about15 minutes. Thereafter, it is passed between a pair of tempering rollers29A and 29B to level the thickness of the metal sheet 1′ so that it hasa required thickness. Then, the metal sheet 1′ is wound as a coil. Byuncoiling the metal sheet 1′ and performing the above-describedembossing, the metal sheet 1′ is allowed to have the construction shownin FIGS. 2 and 3. Then, the embossed metal sheets 1 are layered one uponanother vertically, and the burrs 8 are interlocked with each other tofix the burrs 8 to each other. In this manner, the plate (S) for abattery electrode having the required thickness can be manufactured.

[0069] Needless to say, the convex portion 2 and the concave portion 3may be pyramidal similarly to the first embodiment or conic.

[0070]FIGS. 7 through 10 show the second embodiment. In the secondembodiment, as shown in FIG. 7, rubber rolls 30A and 30B having a smoothsurface are positioned in confrontation with an embossing roll 20; andas shown in FIG. 8, a large number of pores 31 is formed on a flat metalsheet 11 and burrs 8 each projecting in one direction from theperipheral edge of each pore 31 are formed.

[0071] As shown in FIGS. 7A and 7B, when the metal sheet 1′ is passedbetween the embossing roll 20 and the rubber roll 30A, it is pressed bythe rubber roll 30A. As a result, the metal sheet 1′ strikes againstconvex portions 21 of the embossing roll 20, and thus pores 31 areformed thereon. The burrs 8 which are generated as a result of theformation of the pore 31 project toward the rubber roll 30A. Thus, thedirection of the burrs 8 formed on the periphery of the pore 31 isrestricted to one direction (rubber roll side).

[0072] When the metal sheet 1′ is passed between a pair of the embossingroll 20 and the rubber roll 30B, the convex portions 21 of the embossingroll 20 are pressed by the rubber roll 30B again. Thus, the formation ofthe pores 31 which have been made by the pressing contact between therubber roll 30A and the embossing roller can be completed, and the burrs8 are pressingly spread toward the rubber roll 30B.

[0073] The metal sheets 1 manufactured as described above and shown inFIG. 8 are layered vertically one upon another as shown in FIG. 9, andthe burrs 8 are interlocked with each other, with the burrs 8 of thelower metal sheet 1 directed upward and the burrs 8 of the upper metalsheet 1 directed downward. Then, the burrs 8 interlocked with each otherare fused into each other or welded to each other to integrate them witheach other. As a result, spaces 4 can be formed between the upper metalsheet 1 and the lower metal sheet 1.

[0074] When an active substance is charged into a plate (S) for abattery electrode having the construction shown in FIG. 9, the activesubstance is charged into the spaces 4 between the upper metal sheet 1and the lower metal sheet 1 through the pores 31 thereof. The activesubstance charged into the space 4 is held reliably by the metal sheets1 at both sides of the space 4.

[0075] Further, as shown in FIG. 10, it is possible to project the burrs8 in both outward directions and layer them one on the other, with thepores 31 communicating with each other. In this case, the activesubstance is applied between the burrs 8 projecting in both outwarddirections and can be reliably held by the burrs 8.

[0076]FIGS. 11 through 13 show the third embodiment. As shown in FIG.11, two sets each consisting of one embossing roll 20 and two rubberrolls 30A and 30B of the second embodiment shown in FIG. 7 are providedin the third embodiment. In a first set (I), pores 31 are formed andburrs 8 projecting toward the rubber roll 30A side are each formed inthe peripheral edge of each pore 31; in a second set (II), pores 31′ areformed on the metal sheet 1′ at different positions thereof, and burrs8′ projecting toward the rubber roll 30B side and in the directionopposite to the projected direction of the burr 8 are each formed in theperipheral edge of each pore 31′.

[0077] When the metal sheets 1 manufactured as described above and shownin FIG. 12 are layered vertically one on the other, as shown in FIG. 13,the lower burrs 8 and the upper burrs 8 are interlocked with each other.Then, the burrs 8′ interlocked with each other are fused into each otheror welded to each other to integrate them with each other. As a result,spaces are formed between the upper metal sheet 1 and the lower metalsheet 1. When an active substance is charged into the plate (S) for abattery electrode, the active substance is charged into the spacesformed between the upper metal sheet 1 and the lower metal sheet 1through the pores 31 and 31′ thereof and can be held reliably by theupper metal sheet 1 and lower metal sheet 1. It is possible to projectthe burrs 8 of the upper and lower metal sheets 1 in both outwarddirections, with the upper metal sheet 1 and the lower metal sheet 1layered on each other. In this case, the active substance is chargedbetween the burrs 8 projecting in both outward directions and can beheld by the burrs 8.

[0078] In the plate (S) for a battery electrode of the first throughthird embodiments, the metal sheets 1 of the same kind are layered witheach other. As shown in FIGS. 14A through 14C, the metal sheet 1A havingconcave portions and convex portions, pores, and burrs formed thereonand manufactured by the method of the first embodiment, the metal sheet1B having pores and burrs formed thereon in one direction andmanufactured by the method of the second embodiment, and the metal sheet1C having pores and burrs formed thereon in both directions andmanufactured by the method of the third embodiment are combined with oneanother to form the plate (S) for a battery electrode having athickness.

[0079] That is, in the plate (S) for a battery electrode shown in FIG.14A, the metal sheet 1B of the second embodiment is located at the upperand lower sides of the metal sheet 1A of the first embodiment, with themetal sheet 1A sandwiched between the metal sheets lB; and the burrs 8of the metal sheet 1B are directed inward not outward.

[0080] In the plate (S) for a battery electrode shown in FIG. 14B, twometal sheets 1C of the third embodiment are layered one on the other;the metal sheet 1B of the second embodiment is located at the upper andlower sides of the metal sheet 1C; and the burrs 8 of the metal sheet 1Bare directed inward not outward.

[0081] In the plate (S) for a battery electrode shown in FIG. 14C, themetal sheet 1A of the first embodiment is located at the center thereof;the metal sheet 1C of the second embodiment is located at both outersides of the metal sheet 1A; and the metal sheet 1B of the secondembodiment is located at both outer sides of the metal sheet 1C. Theburrs 8 of the metal sheet 1B located outermost are directed inward notoutward.

[0082] Needless to say, as shown in FIG. 15, the shape of the metalsheet 1 which is manufactured by the embossing roll may be formed byvarying at random the projection direction of the burrs 8 which are eachformed on the peripheral edge of each of the pores 31.

[0083] Industrial Applicability

[0084] As apparent from the foregoing description, in the method ofmanufacturing a plate for a battery electrode according to the presentinvention, by using an embossing roll, many fine pores are denselyformed and burrs can be each generated on the periphery of each porewhen many fine pores are formed. Thus, in one processing step, it ispossible to easily manufacture the plate for a battery electrode havingfine pores densely formed thereon, having a high open area ratio, andhaving burrs finely generated at a high occupation percentage.

[0085] In particular, in the first method of the present invention,concave portions and convex portions are formed simultaneously, poresare each formed on the apex of each of the concave portions and convexportions, and burrs can be each formed on the peripheral edge of each ofthe pores to make the apparent thickness of the plate for a batteryelectrode great by means of the concave portions and convex portions andthe burrs. Thus, it is easy to manufacture the plate for a batteryelectrode into which an increased amount of an active substance can becharged. More specifically, it is possible to allow the thickness of theplate for a battery electrode three to 500 times as great as that of aflat metal sheet.

[0086] When the plates manufactured by the method of the presentinvention are layered one upon another, the burrs are interlocked witheach other and the burrs interlocked with each other are fused into eachother or welded to each other to integrate plates with one anothereasily. Thus, the plate for a battery electrode having an integratedlayered structure can be manufactured easily. Further, by adjusting thenumber of metal sheets which are layered one upon another, the platehaving a desired thickness can be obtained.

[0087] Even a plate for a battery electrode manufactured by themanufacturing method of the present invention and consisting of onesheet has many fine pores formed densely. Because an active substance ischarged into the pores, the active substance hardly drops from theplate. Further, because the burrs are formed on the peripheral edge ofeach pore and the occupation percentage of the burr is high, the activesubstance applied to both surfaces of the sheet is held by the burrs andthus hardly drops from the sheet.

[0088] In particular, in the plate consisting of a plurality of sheetslayered one upon another, the active substance charged into spacesbetween the sheets is sandwiched between the sheets. Thus, the activesubstance hardly drops from the plate. Further, when the number ofsheets which are layered one upon another is increased, the plate havinga desired thickness can be formed and moreover, the charge amount of theactive substance can be dramatically increased because spaces arepresent between the sheets of the thick plate. Therefore, theapplication amount of the active substance in the thickness directionthereof can be allowed to be greater than that of the active substancewhich is applied to a conventional flat metal sheet. Thus, the plate hasan improved electricity-collecting performance, thus being capable ofaccomplishing a rapid charging and discharging.

[0089] When the plate is charged with the active substance, it can besmoothly charged because the spaces between the sheets communicate witheach other through the pores.

What is claimed is:
 1. A method of manufacturing a plate for a batteryelectrode comprising the steps of: passing a thin metal sheet between apair of embossing rotation rollers having concave portions and convexportions formed on a peripheral surface thereof to form concave portionsand convex portions on an entire surface of said metal sheet, and formpores each on an apex of each of said concave portions and convexportions and generate burrs each projecting outward from a peripheraledge of each of said pores by a pressing force during formation of saidconcave portions and convex portions.
 2. A method of manufacturing aplate for a battery electrode comprising the steps of: passing a thinmetal sheet between a pair of rotation rollers comprising an embossingroller having concave portions and convex portions formed on aperipheral surface thereof and a rubber roller having smooth outersurface to form pores on said metal sheet and generate burrs eachprojecting toward one side from a peripheral edge of each of said poresby pressing said rubber roller against said convex portions of saidembossing roller.
 3. A method of manufacturing a plate for a batteryelectrode comprising the steps of: passing a thin metal sheetsequentially between first and second sets of rotation rollers eachconsisting of an embossing roller having concave portions and convexportions formed on a peripheral surface thereof and a rubber rollerhaving smooth outer surface to form pores on said metal sheet andgenerate burrs each projecting toward one side from a peripheral edge ofeach of said pores by pressing said rubber roller against said convexportions of said embossing roller when said metal sheet is passingbetween the embossing roller and-the rubber roller of said first set;and passing said metal sheet between the embossing roller and the rubberroller of said second set to form pores on said metal sheet at differentpositions thereof and generate burrs each projecting toward the otherside from said peripheral edge of each of said pores.
 4. The method ofmanufacturing a plate for a battery electrode according to any one ofclaims 1 through 3, wherein metal sheets of the same kind or differentkinds, according to claims 1, 2, and 3, having said pores and said burrseach projecting from the peripheral edge of each of said pores arelayered one upon another; and said burrs of an upper layer metal sheetand said burrs of a lower layer metal sheet adjacent to said upper layermetal sheet are interlocked with each other to integrate said upperlayer metal sheet and said lower layer metal sheet with each other; andspaces between said upper layer metal sheet and said lower layer metalsheet are communicated with each other through said pores.
 5. A platefor a battery electrode manufactured by the method according to any oneof claims 1 through
 4. 6. A plate for a battery electrode which ismanufactured by the method according to claim 4 and comprises a firstmetal sheet, having pores each on an apex of each of concave portionsand convex portions and burrs each projecting outward from a peripheraledge of each of said pores and second metal sheets, having burrsprojecting toward one side and are layered on a surface at both sides ofsaid first metal sheet and sandwiching said first metal sheettherebetween, whose said burrs are projected toward an inner surfaceside of said metal sheets.
 7. A plate for a battery electrode which ismanufactured by the method according to claim 4 and comprises a thirdmetal sheet, having burrs each projecting toward both directions from aperipheral edge of each of said pores and second metal sheets, havingburrs projecting toward one side and are layered on a surface at bothsides of said third metal sheet and sandwiching said third metal sheettherebetween, whose said burrs are projected toward an inner surfaceside of said metal sheets.
 8. The plate for a battery electrodeaccording to any one of claims 5 through 7, wherein said metal sheetconsists of a metal foil or/and metal sheet formed by rolling metalpowder.
 9. The plate for a battery electrode according to claim 8,wherein said metal sheet consists of Ni, Al, Cu, Fe, Ag, Zn, Sn, Pb, Sb,Ti, In, V, Cr, Co, C, Ca, Mo, Au, P, W, Rh, Mn, B, Si, Ge, Se, La, Ga,Ir or an alloy of said elements.
 10. The plate for a battery electrodeaccording to any one of claims 5, 6, 8, and 9, wherein in an electrodeplate for a battery which is manufactured by the method according toclaim 1, a pitch between concave portions and that between convexportions are set to 0.5 mm-2.0 m; and the height of each of said concaveportions and that of said convex portions are set to 0.1 mm-2 mm.
 11. Anelectrode for a battery in which an active substance is charged intospaces of said plate, according to any one of claims 5 through
 10. 12.An electrode for a battery according to claim 11, wherein said activesubstance contains an electrically conductive material.
 13. A batterycomprising said electrode for a battery according to claim 11 or 12.